Empty Directories Remain After Prune

After running vagrant box prune there are still empty directories remaining in the boxes path in the hidden configuration directory ~/.vagrant.d. Is this by design, or is this a bug?

% find boxes/*
boxes/ubuntu-VAGRANTSLASH-jammy64
boxes/ubuntu-VAGRANTSLASH-jammy64/20220616.0.0
boxes/ubuntu-VAGRANTSLASH-jammy64/20220706.0.0
boxes/ubuntu-VAGRANTSLASH-jammy64/20220712.0.0
boxes/ubuntu-VAGRANTSLASH-jammy64/20220712.0.0/virtualbox
boxes/ubuntu-VAGRANTSLASH-jammy64/20220712.0.0/virtualbox/ubuntu-jammy-22.04-cloudimg-configdrive.vmdk
boxes/ubuntu-VAGRANTSLASH-jammy64/20220712.0.0/virtualbox/metadata.json
boxes/ubuntu-VAGRANTSLASH-jammy64/20220712.0.0/virtualbox/ubuntu-jammy-22.04-cloudimg.mf
boxes/ubuntu-VAGRANTSLASH-jammy64/20220712.0.0/virtualbox/box.ovf
boxes/ubuntu-VAGRANTSLASH-jammy64/20220712.0.0/virtualbox/Vagrantfile
boxes/ubuntu-VAGRANTSLASH-jammy64/20220712.0.0/virtualbox/ubuntu-jammy-22.04-cloudimg.vmdk
boxes/ubuntu-VAGRANTSLASH-jammy64/metadata_url
boxes/ubuntu-VAGRANTSLASH-jammy64/20220622.0.0